The construction of reinforced concrete walls using the slurry trench technique as basically disclosed in Veder U.S. Pat. Nos. 2,791,886 and 3,310,952 are well known in the art and basically comprise the formation of the slots or trench sections in the earth in panel form in the presence of a slurry, typically a bentonite slurry which is displaced by concrete to form concrete walls. In the case of steel reinforced walls, a slot is excavated in the earth in the presence of the bentonite slurry, a stop end pipe is inserted in one end of the slot and a steel reinforcing cage is then lowered into the slot. Concrete is then inserted into the slot or trench to displace the bentonite slurry, such concreting typically being done by the tremie pipe technique. After the concrete has hardened, the stop end pipe is removed to form the beginning space for the next succeeding panel section.
There have been many efforts in the past to create a continuous reinforcement in such slurry walls but a simple solution to the problem has eluded the art for many years. In Fehlmann et al U.S. Pat. No. 3,197,946, a steel sheathing such wire netting, perforated sheet metal or the like, permits the reinforcing rods to pass through the meshes at approximate the ends of the slot so as to form a cavity which is filled with the bentonite for the purpose of providing a starting place for the next succeeding excavating and the formation of the joint. In Schoewert U.S. Pat. No. 3,464,665, a steel plate is connected to the template plate in a detachable manner and is left in to bridge the gap. In Kawaski et al U.S. Pat. Nos. 3,938,292 and 3,990,200, protruding reinforcements and sealing means for positioning the protruding reinforcements are provided and inflattable elements are utilized to shield the protruding reinforcements, and dam or block the concrete and form the open space for the next succeeding excavation and coupling between two units. In Irwin-Childs U.S. Pat. No. 3,798,914, cruciform shaped coupling elements are utilized to form the coupling between adjacent panel elements. In Novet U.S. Pat. Nos. 3,513,572 an intermediate reinforcing cage is utilized. In some cases, such as in Tamaro U.S. Pat. No. 4,005,582, flanges on connected on H-beam pairs provide the coupling between the steel reinforcements. In some cases, the ends of the elements and their associated reinforcing cages are shaped to provide overlap between successive panel elements. Finally, in Piccagli U.S. Pat. No. 3,796,054, flexible membranes are carried in the stop end pipes which remain in place when the stop end has been removed so as to provide a barrier to the flow of fluids.
The present invention provides a simple solution to a problem that has eluded the art for many years. According to the invention the excavation initially begins as described in the aforementioned Veder U.S. Pat. No. 3,310,952. In this case, the stop end pipe is preferably rectangular, as has been used heretofore, and has a pair of channels formed adjacent the sides thereof. Into each channel is placed an expansible joint reinforcement cage. In one preferred embodiment, this expansible joint reinforcement cage comprises a pair of channels which are interconnected by pivoted lengths of rebars of appropriate lengths. One of the channels facing the side in which concrete is to be poured is provided with concrete anchors which extend into the excavated space. The two channels are in a "closed" position and may have styrofoam or other means to prevent concrete from entering in between them during the pour and may be fastened together at the top. the concrete anchor reinforcing bars which extend from the channel into the space to be poured assure that this assembly will be firmly embedded into the newely poured concrete panel. When the rectangular stop end piece has been pulled out at the end of the pour, any frictional effects during the pulling out of the panel will tend to keep the channel assembly "closed". The adjacent panel section or slot is then excavated, a reinforcement cage is then placed inside this newely excavated panel section. At this point, the expandable reinforcing cage is expanded by disconnecting the channels at the top, the one sticking up is tapped vertically which will result in its swinging out until the linkage reinforcing bars are in a horizontal position. These constitute the continuity of the reinforcement and the second panel section is then poured or filled with concrete.
The invention has the advantage that it is simple, relatively inexpensive, very workable and easy to install, since normally continuity of the reinforcement is located in the upper portion of the panels and does not normally extend to the full depth. Moreover, since the joint reinforcement cage is expandable, it is normally maintained in an out-of-the-way and protected position during the excavation of the adjoining panel section and thereby avoids interference with the extensive horizontal protrusions in the joint reinforcing sections as is performed in the prior art such as in the above-mentioned Kawasaki et al patents and Fehlmann et al patents.